Generally, an optical fiber comprises a core through which an optical signal is transmitted, a clad for enclosing the core, and a sheath layer for protecting the core and the clad.
In a case where a single optical fiber is used for a security system, the optical fiber is installed to measure dynamic or static changes in an optical signal transmitted through the optical fiber, or to measure physical fluctuation in the optical fiber using back scattering of the optical signal.
A technique regarding a security system using an optical fiber is disclosed in PCT Application No. PCT/KR02/0164 entitled “Security System Using Optical Fiber and Method of Controlling the Same” and filed on Aug. 30, 2002 by the present applicant. Particularly, when the optical fiber is connected to an optical transmitter module and an optical receiver module in the invention of this application, an optical contact means capable of easily connecting optical fibers that have been cut to have appropriate lengths in place is required.
Further, the optical contact means for use in such a security system is required to have the function of avoiding optical loss and shielding noises from the outside by completely sealing a contact portion.
Moreover, the optical contact means for use in such a security system is required to have the function of protecting the security system in such a manner that when external force exceeding a predetermined value is applied to the optical fiber, the optical fiber is easily separated from the security system to prevent the security system from being damaged.
Further, the optical contact means for use in such a security system is required to have the function of allowing a damaged or antiquated optical fiber to be easily replaced and reinstalled from the outside.
However, since the conventional optical contact means has a structure for fixing the optical fiber by compressing a sheath of the optical fiber with a metal piece, inexact dimensions of the metal piece may damage the core or clad of the optical fiber. Therefore, there is a problem that since the metal piece should be precisely machined, manufacturing costs thereof are increased.
Furthermore, there is a problem that if the optical contact means is molded with synthetic resin or the like to be completely sealed, it is impossible to properly adjust the length of the optical fiber and reinstall the optical fiber according to installation conditions.